actions/README.md

scotty-git actions

Shared Forgejo Actions that any repository on git.scotty-world.com can use.

Action	What it does
kaniko-build	Build a container image from your repository and push it to a registry

Actions on this server are referenced by their full URL. Short names such as actions/checkout still resolve to data.forgejo.org, as usual.

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kaniko-build

Builds a Docker/OCI image from the repository your job checked out, using Kaniko, and pushes it to the registry you choose.

Why Kaniko and not docker build: the scotty-git runner is a shared, long-lived machine. Giving workflows the Docker daemon would hand every workflow root access to that machine and leave image layers on its disk. Kaniko builds inside the step's own container instead: no root, no privileged mode, nothing left behind. The build happens the same way as on a GitHub-hosted runner; only the engine differs.

Quick start: push to scotty-git's own container registry

No cloud account needed. Create a token at Settings → Applications with the write:package scope, and save it in your repository as the secret REGISTRY_TOKEN (Settings → Actions → Secrets). Then:

# .forgejo/workflows/image.yml
name: Build image
on:
  push:
    branches: [main]

jobs:
  image:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: https://git.scotty-world.com/scotty-git/actions/kaniko-build@v1
        with:
          destination: git.scotty-world.com/${{ github.repository }}:${{ github.sha }}
          username: ${{ github.actor }}
          password: ${{ secrets.REGISTRY_TOKEN }}

The image appears under your repository's Packages tab.

Google Artifact Registry

Use a service account that can push to your repository only (role Artifact Registry Writer granted on that one repository, nothing project-wide). Save its JSON key as a secret in your repository, never at organisation or instance level:

      - uses: https://git.scotty-world.com/scotty-git/actions/kaniko-build@v1
        with:
          destination: asia-south1-docker.pkg.dev/my-project/my-repo/my-app:${{ github.sha }}
          gcp_key_json: ${{ secrets.GCP_AR_PUSH_KEY }}
          cache_repo: asia-south1-docker.pkg.dev/my-project/my-repo/my-app-cache

Docker Hub, GitHub Container Registry, others

        with:
          destination: docker.io/my-user/my-app:1.2.3
          username: my-user
          password: ${{ secrets.DOCKERHUB_TOKEN }}

Inputs

Input	Default	Description
destination		Image reference(s), separated by commas or new lines. Required unless push is false.
context	.	Build context, relative to the repository root.
dockerfile	Dockerfile	Dockerfile path, relative to the repository root.
push	true	false builds without pushing, e.g. to check that a PR still builds.
registry	host of the first destination	Registry the credentials are for.
username / password		Registry login. Always pass the password from a secret.
gcp_key_json		Google service-account key JSON, instead of username/password.
cache_repo		Registry repository for the layer cache. Speeds up rebuilds; stored in the registry, not on the runner.
build_args		One KEY=VALUE per line.
extra_args		Extra Kaniko flags, space-separated (advanced).

Output: digest, the sha256 digest of the pushed image.

Good to know

• Check out first. The action builds whatever actions/checkout put in the workspace.
• Credentials stay yours. This action stores no credentials. Each repository passes its own secret, and the login exists only inside the step's container for the length of the build.
• The runner is shared. Image builds take a few minutes on a small machine and other jobs queue behind them. Use cache_repo to keep rebuilds short.
• The Kaniko version is pinned (v1.23.2, by digest) in kaniko-build/Dockerfile, so a build tool update can never change your builds without a reviewed change here.
• Versions: use @v1 to get compatible fixes. Breaking changes get a new major tag.

Runner limits (all workflows on scotty-git)

Every job on the shared scotty-git runner is limited to 1.5 GB of memory, so that no workflow can take down the git server it runs next to. Each job can read the limit from the environment variable SCOTTY_GIT_JOB_MEMORY_LIMIT.

If a step fails with exit code 137, it was stopped because it used more than 1.5 GB. Common fixes: run tests with fewer parallel workers, avoid loading whole datasets into memory, or split the job. kaniko-build prints this explanation itself. For other steps the runner can only report the exit code, so this is the place to look it up. If your workload genuinely needs more, ask the scotty-git admins (every memory stop is logged on the runner: journalctl -t ci-memory-limit).

Changing this action

Open a pull request. The Self-test kaniko-build workflow builds a small test image with your change before it can affect anyone's workflow.